Semmelweis University
More than
Medical 250 years
Chemistry in the
Problems
service of health
, Medical Chemistry – Problems
I. Concentration
1. How many grams of solid NaCl are required to prepare 75 g of a 0.9 m/m% solution? (0.675 g)
2. 15 grams of sodium hydroxide (NaOH) are mixed with 400 g of water. Calculate the molarity of
the solution (the density of the solution is 1 g/ml). (0.9 M)
3. What is the m/V% concentration of a 20 m/m% solution? The density of the solution is 1.17 g/ml.
(23.4 m/V%)
4. 75 ml of an aqueous solution contain 1.5 mol of NaCl. Calculate the m/V% concentration of the
solution. The molar mass of NaCl is 58.5 g/mol. (117 m/V%)
5. How many grams of solid NaCl are to be dissolved in 500 ml water to prepare a 20 m/m% solution?
(125 g)
6. The concentration of a stock solution of sulfuric acid is 94 m/m% and its density is 1.84 g/ml. This
stock solution is diluted to a final volume of 0.5 l. The concentration of the diluted solution is 10
m/m% and its density is 1.1 g/ml. How many ml of the stock solution were diluted? (31.8 ml)
7. Calculate the V/V% concentration of a solution prepared by mixing 20 ml glycerol and 100 ml
water. (16.6 V/V%)
8. What is the molarity of a 28 m/m% KOH solution? The density of the solution is 1.27 g/ml and
the molar mass of KOH is 56 g/mol. (6.35 M)
9. Calculate the molarity of a 3 m/V% solution with a density of 1.0 g/ml. The molar mass of the
solute is 158 g/mol. (0.19 M)
10. The concentration of a sulfuric acid solution is 96 m/m% and its density is 1.84 g/cm3? Convert
its concentration to m/V%. (176.64%)
11. The molar mass of a substance is 80 g/mol. 4 g of this substance are dissolved in 100 ml of water,
yielding 101.5 ml of solution. What is the molarity and molality of the solution? (cM = 0.493 M;
cm = 0.5 mol/kg)
12. 20 g of glucose (molar mass: 180 g/mol) are dissolved in 80 ml of water. Calculate the mole
fraction of glucose and water in the solution, respectively. (Xglc = 0.024, XH2O = 0.976)
13. 32 ml of a KOH solution are diluted with water to a final volume of 240 ml and a final concentra-
tion of 0.04 mol/l. Calculate the concentration of the original solution in m/V%. Relative atomic
masses: H = 1; O = 16; K = 39. (1.68 m/V%)
14. We aim to prepare 200 ml of a NaOH solution with a molar concentration of 0,1 M. How many
grams of NaOH are to be dissolved for that? (0.8 g)
15. Calculate the concentration of a 2 N sulfuric acid solution in m/V%. (The molar mass of sulfuric
acid is 98 g/mol.) (9.8 m/V%)
16. We aim to prepare 0.5 l of a solution containing 0.1 M NaCl and 0.5 M glucose. The concentration
of the NaCl and glucose stock solutions is 5 M and 1 M, respectively. How shall we prepare the
solution? (0,01 liter 5 M NaCl + 0,25 liter 1 M glucose mixed with 0,24 liter H2O)
17. What is the normality of a NaOH solution prepared by dissolving 20 g of NaOH in water? The
volume of the solution is 100 ml. (5 N)
1
, Medical Chemistry – Problems
II. Strong acids
1. What is the pH of a 1 mM hydrochloric acid solution? (pH = 3)
2. What is the pH of a 0.1 M hydrochloric acid solution? (pH = 1)
3. What is the pH of a 1 M hydrochloric acid solution? (pH = 0)
4. What is the pH of a 1 mM NaOH solution? (pH = 11)
5. What is the pH of a 0.1 M NaOH solution? (pH = 13)
6. What is the pH of a 1 M NaOH solution? (pH = 14)
7. What is the pH of a 0.02 M hydrochloric acid solution? (pH = 1.7)
8. What is the pH of a 2 mM NaOH solution? (pH = 11.3)
9. What is the pH of a 4 mM nitric acid solution? (pH = 2.4)
10. What is the molarity of a NaOH solution with a pH value of 12.398? (cM = 0.025 M)
11. What is the molarity of a nitric acid solution with a pH value of 2.4? (cM = 4 mM)
12. What ist he molarity of a hydrochloric acid solution of pH = 2.7? (cM = 2 mM)
13. How many grams of solid NaOH are required to prepare 100 ml NaOH solution with a pH of 12?
(0.04 g)
14. How many grams of nitric acid can be found in 500 ml of a solution with a pH value of 3? The
molar mass of the acid is 63 g/mol. (0.0315 g)
15. How many ml of a 1 M NaOH stock solution are to be diluted with water to prepare 200 ml solution
with a pH of 12? (2 ml)
16. How can we prepare 100 ml of a nitric acid solution with a pH value of 2 from a 1 M nitric acid
stock solution? (1 ml 1 M nitric acid + 99 ml water)
17. How many ml of a 0.4 M hydrochloric acid solution should be mixed with 10 ml of a 0.1 M NaOH
to get a neutral solution? (2.5 ml)
18. How many ml of a 0.25 M NaOH solution are to be mixed with 5 ml of a 0.1 M H2SO4 to get a
neutral solution? (4 ml)
19. How many grams of solid NaOH are to be dissolved in 500 ml of a pH = 2 sulfuric acid solution
to neutralize it? (0.2 g)
20. 0.4 g of NaOH has to be dissolved in 100 ml of hydrochloric acid solution in order to neutralize it
completely. What is the pH of the original hydrochloric acid solution? (pH = 1)
21. We aim to find out the concentration of a hydrochloric acid solution. Mixing 10 ml of this HCl
solution with 12 ml of a 0.1 M NaOH solution yields a neutral solution. What is the molarity of
the HCl solution? (0.12 M)
22. 8 ml of a 0.2 M hydrochloric acid solution are mixed with 12 ml of a 0.1 M NaOH. Calculate the
pH of the resulting solution. (pH = 1.7)
23. 5 ml of a 0.6 M NaOH solution are mixed with 5 ml of a 0.4 M HCl solution. What is the pH of
the mixture? (pH = 13)
24. 10 ml of a 0.1 M sulfuric acid solution are mixed with 25 ml of a 0.1 M NaOH solution. What is
the pH of the mixture? (pH = 12.155)
25. The pH of a HCl solution is 1.7. How many mols of solid NaOH shall we dissolve in 100 ml of
this solution to raise its pH to 12? (3 mmol)
26. 20 ml of a pH = 2.3 hydrochloric acid solution and 30 ml of a pH = 11.6 solution of a strong base
are mixed. What is the pH of the mixture? (pH = 10.6)
2
, Medical Chemistry – Problems
III. Weak acids
1. What is the pH of a 0.1 M acetic acid solution (pKa = 4.7)? What is the degree of dissociation of
the acid in this solution? (pH = 2.85, α = 0.014)
2. What is the pH of a 0.01 M acetic acid solution (pKa = 4.7)? What is the degree of dissociation of
the acid in this solution? Compare the result with that of the previous problem and explain the
difference. (pH = 3.35, α = 0.044)
3. What is the pH of a 0.1 M solution of a weak acid given that the degree of dissociation at this
concentration is = 0.01. (pH = 3)
4. Calculate the acid dissociation constant in a 0.2 M solution of a weak acid taking into account that
the degree of dissociation is = 0.005 in this solution. (pKa = 5.3, Ka = 5.01 · 10–6)
5. The acid dissociation constant of a weak acid is Ka = 3.2 10–4. Calculate the degree of dissociation
of the acid in a 0.02 M solution. (α = 0.119)
6. Calculate the pH of a 0.05 M solution of sodium acetate. The acid dissociation constant of acetic
acid is Ka = 2 · 10–5. (pH = 8.7)
7. What is the pH of a 10 mM solution of a weak acid (Ka = 10–4)? (pH = 3)
8. The pH of a 0.01 M solution of a weak monoprotic acid is 4. Calculate the dissociation constant
and degree of dissociation of the acid. (α = 0.01; Ka = 1.01 · 10–6)
9. What is the pH of a 0.1 M solution of a weak acid (Ka = 1.4 10–5)? How would the pH change
upon hundredfold dilution of the acid? (pH1 = 2.925; pH2 = 3.925)
10. The degree of dissociation of a 0.1 M solution of a weak acid is α = 1.3%. What would be the
molar concentration of the acid if the degree of dissociation were α = 90%? (cM = 2.11 · 10–6 M)
11. The pH of a 0.1 M solution of a weak acid is 2.6. Calculate the dissociation constant and the degree
of dissociation of the acid. (α = 0.025; Ka = 6.3 · 10–5)
12. Calculate the pH of a 1 m/V% solution of acetic acid (pKa = 4.7). (pH = 2.74)
13. Calculate the pH of a 0.035 M solution of a weak base (pKa = 9.6)? (pH = 11.07)
14. The dissociation constant of a weak acid is 1.6 10–6. Calculate the pH and the degree of dissoci-
ation of a 1 mM solution of this acid. (pH = 4.395; α = 0.04)
3
More than
Medical 250 years
Chemistry in the
Problems
service of health
, Medical Chemistry – Problems
I. Concentration
1. How many grams of solid NaCl are required to prepare 75 g of a 0.9 m/m% solution? (0.675 g)
2. 15 grams of sodium hydroxide (NaOH) are mixed with 400 g of water. Calculate the molarity of
the solution (the density of the solution is 1 g/ml). (0.9 M)
3. What is the m/V% concentration of a 20 m/m% solution? The density of the solution is 1.17 g/ml.
(23.4 m/V%)
4. 75 ml of an aqueous solution contain 1.5 mol of NaCl. Calculate the m/V% concentration of the
solution. The molar mass of NaCl is 58.5 g/mol. (117 m/V%)
5. How many grams of solid NaCl are to be dissolved in 500 ml water to prepare a 20 m/m% solution?
(125 g)
6. The concentration of a stock solution of sulfuric acid is 94 m/m% and its density is 1.84 g/ml. This
stock solution is diluted to a final volume of 0.5 l. The concentration of the diluted solution is 10
m/m% and its density is 1.1 g/ml. How many ml of the stock solution were diluted? (31.8 ml)
7. Calculate the V/V% concentration of a solution prepared by mixing 20 ml glycerol and 100 ml
water. (16.6 V/V%)
8. What is the molarity of a 28 m/m% KOH solution? The density of the solution is 1.27 g/ml and
the molar mass of KOH is 56 g/mol. (6.35 M)
9. Calculate the molarity of a 3 m/V% solution with a density of 1.0 g/ml. The molar mass of the
solute is 158 g/mol. (0.19 M)
10. The concentration of a sulfuric acid solution is 96 m/m% and its density is 1.84 g/cm3? Convert
its concentration to m/V%. (176.64%)
11. The molar mass of a substance is 80 g/mol. 4 g of this substance are dissolved in 100 ml of water,
yielding 101.5 ml of solution. What is the molarity and molality of the solution? (cM = 0.493 M;
cm = 0.5 mol/kg)
12. 20 g of glucose (molar mass: 180 g/mol) are dissolved in 80 ml of water. Calculate the mole
fraction of glucose and water in the solution, respectively. (Xglc = 0.024, XH2O = 0.976)
13. 32 ml of a KOH solution are diluted with water to a final volume of 240 ml and a final concentra-
tion of 0.04 mol/l. Calculate the concentration of the original solution in m/V%. Relative atomic
masses: H = 1; O = 16; K = 39. (1.68 m/V%)
14. We aim to prepare 200 ml of a NaOH solution with a molar concentration of 0,1 M. How many
grams of NaOH are to be dissolved for that? (0.8 g)
15. Calculate the concentration of a 2 N sulfuric acid solution in m/V%. (The molar mass of sulfuric
acid is 98 g/mol.) (9.8 m/V%)
16. We aim to prepare 0.5 l of a solution containing 0.1 M NaCl and 0.5 M glucose. The concentration
of the NaCl and glucose stock solutions is 5 M and 1 M, respectively. How shall we prepare the
solution? (0,01 liter 5 M NaCl + 0,25 liter 1 M glucose mixed with 0,24 liter H2O)
17. What is the normality of a NaOH solution prepared by dissolving 20 g of NaOH in water? The
volume of the solution is 100 ml. (5 N)
1
, Medical Chemistry – Problems
II. Strong acids
1. What is the pH of a 1 mM hydrochloric acid solution? (pH = 3)
2. What is the pH of a 0.1 M hydrochloric acid solution? (pH = 1)
3. What is the pH of a 1 M hydrochloric acid solution? (pH = 0)
4. What is the pH of a 1 mM NaOH solution? (pH = 11)
5. What is the pH of a 0.1 M NaOH solution? (pH = 13)
6. What is the pH of a 1 M NaOH solution? (pH = 14)
7. What is the pH of a 0.02 M hydrochloric acid solution? (pH = 1.7)
8. What is the pH of a 2 mM NaOH solution? (pH = 11.3)
9. What is the pH of a 4 mM nitric acid solution? (pH = 2.4)
10. What is the molarity of a NaOH solution with a pH value of 12.398? (cM = 0.025 M)
11. What is the molarity of a nitric acid solution with a pH value of 2.4? (cM = 4 mM)
12. What ist he molarity of a hydrochloric acid solution of pH = 2.7? (cM = 2 mM)
13. How many grams of solid NaOH are required to prepare 100 ml NaOH solution with a pH of 12?
(0.04 g)
14. How many grams of nitric acid can be found in 500 ml of a solution with a pH value of 3? The
molar mass of the acid is 63 g/mol. (0.0315 g)
15. How many ml of a 1 M NaOH stock solution are to be diluted with water to prepare 200 ml solution
with a pH of 12? (2 ml)
16. How can we prepare 100 ml of a nitric acid solution with a pH value of 2 from a 1 M nitric acid
stock solution? (1 ml 1 M nitric acid + 99 ml water)
17. How many ml of a 0.4 M hydrochloric acid solution should be mixed with 10 ml of a 0.1 M NaOH
to get a neutral solution? (2.5 ml)
18. How many ml of a 0.25 M NaOH solution are to be mixed with 5 ml of a 0.1 M H2SO4 to get a
neutral solution? (4 ml)
19. How many grams of solid NaOH are to be dissolved in 500 ml of a pH = 2 sulfuric acid solution
to neutralize it? (0.2 g)
20. 0.4 g of NaOH has to be dissolved in 100 ml of hydrochloric acid solution in order to neutralize it
completely. What is the pH of the original hydrochloric acid solution? (pH = 1)
21. We aim to find out the concentration of a hydrochloric acid solution. Mixing 10 ml of this HCl
solution with 12 ml of a 0.1 M NaOH solution yields a neutral solution. What is the molarity of
the HCl solution? (0.12 M)
22. 8 ml of a 0.2 M hydrochloric acid solution are mixed with 12 ml of a 0.1 M NaOH. Calculate the
pH of the resulting solution. (pH = 1.7)
23. 5 ml of a 0.6 M NaOH solution are mixed with 5 ml of a 0.4 M HCl solution. What is the pH of
the mixture? (pH = 13)
24. 10 ml of a 0.1 M sulfuric acid solution are mixed with 25 ml of a 0.1 M NaOH solution. What is
the pH of the mixture? (pH = 12.155)
25. The pH of a HCl solution is 1.7. How many mols of solid NaOH shall we dissolve in 100 ml of
this solution to raise its pH to 12? (3 mmol)
26. 20 ml of a pH = 2.3 hydrochloric acid solution and 30 ml of a pH = 11.6 solution of a strong base
are mixed. What is the pH of the mixture? (pH = 10.6)
2
, Medical Chemistry – Problems
III. Weak acids
1. What is the pH of a 0.1 M acetic acid solution (pKa = 4.7)? What is the degree of dissociation of
the acid in this solution? (pH = 2.85, α = 0.014)
2. What is the pH of a 0.01 M acetic acid solution (pKa = 4.7)? What is the degree of dissociation of
the acid in this solution? Compare the result with that of the previous problem and explain the
difference. (pH = 3.35, α = 0.044)
3. What is the pH of a 0.1 M solution of a weak acid given that the degree of dissociation at this
concentration is = 0.01. (pH = 3)
4. Calculate the acid dissociation constant in a 0.2 M solution of a weak acid taking into account that
the degree of dissociation is = 0.005 in this solution. (pKa = 5.3, Ka = 5.01 · 10–6)
5. The acid dissociation constant of a weak acid is Ka = 3.2 10–4. Calculate the degree of dissociation
of the acid in a 0.02 M solution. (α = 0.119)
6. Calculate the pH of a 0.05 M solution of sodium acetate. The acid dissociation constant of acetic
acid is Ka = 2 · 10–5. (pH = 8.7)
7. What is the pH of a 10 mM solution of a weak acid (Ka = 10–4)? (pH = 3)
8. The pH of a 0.01 M solution of a weak monoprotic acid is 4. Calculate the dissociation constant
and degree of dissociation of the acid. (α = 0.01; Ka = 1.01 · 10–6)
9. What is the pH of a 0.1 M solution of a weak acid (Ka = 1.4 10–5)? How would the pH change
upon hundredfold dilution of the acid? (pH1 = 2.925; pH2 = 3.925)
10. The degree of dissociation of a 0.1 M solution of a weak acid is α = 1.3%. What would be the
molar concentration of the acid if the degree of dissociation were α = 90%? (cM = 2.11 · 10–6 M)
11. The pH of a 0.1 M solution of a weak acid is 2.6. Calculate the dissociation constant and the degree
of dissociation of the acid. (α = 0.025; Ka = 6.3 · 10–5)
12. Calculate the pH of a 1 m/V% solution of acetic acid (pKa = 4.7). (pH = 2.74)
13. Calculate the pH of a 0.035 M solution of a weak base (pKa = 9.6)? (pH = 11.07)
14. The dissociation constant of a weak acid is 1.6 10–6. Calculate the pH and the degree of dissoci-
ation of a 1 mM solution of this acid. (pH = 4.395; α = 0.04)
3
